Added GitHub actions test timeout limit and workflow concurrency

Author: bert-mccutchen

.github/workflows/main.yml

@@ -8,9 +8,13 @@ on:
   pull_request:
     branches:
       - main
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
 jobs:
   macos_regression:
     runs-on: macos-latest
+    timeout-minutes: 3
     strategy:
       matrix:
         ruby:
@@ -29,6 +33,7 @@ jobs:
       run: bundle exec rake
   ubuntu_regression:
     runs-on: ubuntu-latest
+    timeout-minutes: 3
     strategy:
       matrix:
         ruby: